A periscope comprises a head prism which is pivotable, for sighting, about a horizontal axis and which deviates light coming from viewed objects towards an objective disposed in the upper part. After the objective, the beam of light passes through a set of image-conveying media. The beam of light is then reflected, at the foot of the periscope, at one or several reflectors, towards one or several eyepieces.
Equipping periscopes with two objectives, one adapted to day viewing and the other to night viewing, has been tried. These two objectives are then centered on two parallel and separate optical axes. The images given by these two objectives are then collected by the set of image-conveying media which is common to the two channels. The space these objectives occupy is a disadvantage in making a submarine periscope head.